mysql创建表加注释

CREATE TABLE table_name (
    column_name data_type [NOT NULL | NULL] [DEFAULT default_value] [AUTO_INCREMENT] [UNIQUE [KEY]] [[PRIMARY] KEY],
    ...
) ENGINE=engine_name DEFAULT CHARSET=charset_name COMMENT='table_comment';

ALTER TABLE table_name
MODIFY COLUMN column_name data_type [NOT NULL | NULL] [DEFAULT default_value] [AUTO_INCREMENT] [UNIQUE [KEY]] [[PRIMARY] KEY]
COMMENT 'column_comment';

CREATE TABLE employees (
    employee_id INT AUTO_INCREMENT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    email VARCHAR(100) UNIQUE,
    phone_number VARCHAR(15),
    hire_date DATE,
    job_id INT,
    salary DECIMAL(8, 2),
    commission_pct DECIMAL(2, 2),
    manager_id INT,
    department_id INT
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='Contains information about employees in the company';

ALTER TABLE employees
MODIFY COLUMN employee_id INT AUTO_INCREMENT PRIMARY KEY COMMENT 'Unique identifier for each employee';